The present invention is directed to a device and method for testing the condition of fluid control devices, particularly fluid control valves found in automatic transmissions of vehicles. More particularly, the present invention is directed to a device and method for determining whether such a fluid control device exhibits an acceptable flow rate.
Modern automatic transmissions commonly employ a plurality of fluid control valves in their design and construction. Such valves may take the form of, for example, shift solenoids, pressure regulating solenoids, and pressure switches.
These valves may be of various design, but typically operate to regulate or restrict the passage of fluid through a portion of the automatic transmission. For example, a valve may include a housing containing a solenoid or similar actuating device that is coupled to a movable valve spool. The valve spool moves within a chamber in the housing and acts to regulate the flow of fluid through the valve. As such, these valves can be used to also regulate the flow of fluid through an automatic transmission, thereby providing for the desired shifting operation thereof.
Such a valve may experience operational problems, or may become inoperable, for a number of reasons. For example, it is possible for contaminants to be or become present in the automatic transmission fluid supply and to be circulated through the valve. These contaminants may comprise debris such as pieces of dirt or gasket material, for example. When traveling through a valve, one or more pieces of debris may become lodged on the spool or in the chamber within which the spool moves. If the piece of debris is of significant size, or a sufficient quantity of debris accumulates, movement of the valve spool and operation of the valve can be negatively affected.
Many automatic transmission valves employ a valve spool having a distal end that is adapted to press against a spring-loaded check valve or similar device. Hence, it is also possible that the distal end of the valve spool may become deformed after long term and repeated contact with such a check valve. Such a deformation of the valve spool can also cause a malfunction of the valve and negatively affect its ability to regulate fluid flow through the transmission.
An automatic transmission as a whole may malfunction or fail for a number of reasons, not all of which are related to the fluid control valves located therein. Further, an automatic transmission malfunction or failure may be due to a problem with one or more of its fluid control valves, while a remainder of such valves may be operating normally.
Because of the significant cost involved with replacing an automatic transmission, malfunctioning or failed transmissions are often rebuilt or remanufactured. In such a case, it is desirable to know whether the valves of the automatic transmission are in proper working order. While certain known devices have been constructed to test these valves while they are still in the transmission, much of such testing is actually done after the valves have been removed.
As stated previously, a single automatic transmission may contain a number of such valves. Consequently, when rebuilding an automatic transmission, or testing valves from one transmission for use in another, it is also desirable to have a means by which the valves can be quickly, accurately and reliably checked for proper operation. This is especially relevant in a manufacturing environment, such as an automotive transmission manufacturing environment, where a high volume of valves may be tested on a regular basis.
Currently known devices and methods do not satisfy these requirements. The aforementioned devices designed to test valves while they are still installed to a transmission are not readily usable in this setting. Further, such valves can perform improperly for a number of reasons: some of which can render the valve unusable and some of which may be easily corrected. For example, a valve may exhibit unacceptable flow characteristics due to the presence of minor contamination, or due to a more serious problem—such as a deformation of a valve stem or spool. Currently known devices and methods for testing valves cannot readily distinguish between such problems, thereby resulting in the unnecessary disposal of useable valves.